I downloaded SiN episodes via steam, and the download reads '100% ready'. However, when i try and start the game, all i get is a low res version of my desktop, and task manager reads SiN as 'not responding'. I contacted Valve about the problem, but so far everything they have suggested has not worked. All my drivers are up to date, my system is healthy. What is going wrong? I can run HL2 with all the bells and whistles, (also a steam download) so why wont SiN even start?